The present disclosure generally relates to a prosthesis comprising an element for receiving a stump fitted on or established by a support part, a distal prosthetic part assembled on said support part by a pivot link forming a pivot joint to enable flexion or extension of the distal prosthetic part with respect to the support part, and an absorbing system to absorb the flexion or extension efforts.
Persons having a lower limb amputated between the knee and the hip have already been offered the possibility of being able to ski again.
In a first approach, amputated persons skied on a single leg and were equipped with crutches provided with small skis at their ends for them to be able to keep their balance.
In a second approach, it was proposed to give amputated persons the possibility of skiing on two lower limbs with a prosthetic material performing functions close to those of a real lower limb under particular conditions, such as the triple flexion position (hip, knee, ankle) with an absorber enabling the contours of a ski slope to be absorbed.
Articulated prostheses for the lower limb comprising an element for receiving a thigh stump of a patient thus exist. The element can then be fitted onto a leg by a pivot link the pin of which forms a knee joint to enable flexion or extension of the leg with respect to the element. A jack enables the flexion or extension efforts to be absorbed.
In the example of FIGS. 1 and 2, a support part 1, on which the element for receiving 6 are fitted, is itself fitted on leg 3 by a pivot link 2 so as to form a knee joint. Jack 4 is fitted on the one hand on a front part of leg 3 (part facing a foot 5), and on the other hand on a rear part (zone at the level of which the angle a, closes in case of flexion) of support part 1.
FIG. 1 illustrates the position of the prosthesis in flexion with an angle a of 155 degrees between leg 3 and element for receiving 6 at the level of the flexion. FIG. 2 illustrates an angle a of 110 degrees. With angle [alpha] at 155 degrees, the force Fjack exerted by jack 4 is about 2500 Newton whereas at 110 degrees the force Fjack exerted by the same jack 4 is about 5100 N. The more the prosthesis is flexed, the more the jack will in fact have difficulty in counteracting the flexion, and the user then finds him/herself without a shock absorbing system which may lead to breaking at the level of the joint. Furthermore, the convenience of use of the prosthesis is thereby greatly impaired.